JPS61209777A - Manufacture of regulating ring for high-pressure rotor in steam turbine regulating ring - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a regulating wheel for a high-pressure rotor in a steam turbine.
MoV A number of vane units made of solid material such as steel are assembled as one ring body and welded together at the base plate and cover plate of the vane unit, and then the ring body is mounted on a high pressure rotor after heat treatment and machining and testing. It relates to a type of welding onto a disk. The invention also relates to an adjustment wheel manufactured in this way.

In order to achieve good part load characteristics of conventional technology steam turbines,
Often an impulse stage is used as a regulating stay in front of the reaction stage of the high pressure turbine. This impulse stage is designed to have a small degree of recoil, so it can be operated even in busy areas. With the partial inflow, the steam flow and thus the output of the turbine is regulated. In contrast, the subsequent reaction stages operate with full inflow during all loads.

The adjustment stage usually consists of a row of guide vanes and a row of rotary vanes, the guide vane row being called a nozzle and the rotating vane row together with the associated rotor section being called an impeller.

The impeller is manufactured by welding a pre-prepared adjustment wheel onto the relevant rotor part. The adjusting wheel itself is also a welded structure. In general, welding creates a more concentrated and homogeneous bond than any other mechanical bond. The connection between the vane and the rotating shaft can therefore safely withstand static forces due to centrifugal forces and dynamic forces caused by intermittent steam flows even at maximum temperatures.

A method for manufacturing an adjusting wheel of the type mentioned at the outset is already known.

In the known method, the vane unit with its vane part, base plate part and bracket part is machined out of a bar stock. The individual vane units are butt-welded at their base plate as well as at their cover plate into a ring body. This ring body is then welded onto the rerotor by submerged arc welding with a large U-shaped groove. After stress moderation, the entire rotor is turned and the root portions prone to cracking are removed.

In this known method, the commer plates of the vane unit are welded together in groups in order to avoid vibrational excitation by the steam flow from the nozzle. Each group consists of three, four or more vane units. The groups are not connected to each other in force plates.

To form a closed ring body, the individual vane units or groups of vane units must be connected to one another in the area of the base plate. For this reason, the base plate is designed to have a significantly larger radial dimension than the cover plate. The weld seam does not extend to the wall of the base plate that is in contact with the steam flow.

As a result, the root area of the weld seam in the base plate is removed by drilling holes in the outer circumference of the rotor disk,
Removal of this root area gives the welded adjustment wheel a distinctive appearance.

The material of the blade unit is a material that is difficult to weld, such as X22.
It is CrMoV121. Nevertheless, welded joints with similar strength and toughness must be formed from this material. For this purpose, the weld metal must be tempered. However, the weld metal used, that is, the weld metal whose carbon content is increased so as not to become two-phase, does not transform slowly at a preheating temperature of about 300 °C like low alloy steel, but remains austenite. It has the property of being able to undergo transformation only by cooling. Therefore, it is common to cool the welded adjustment wheel so that the desired transformation occurs. The resulting martensite is softened and toughened by subsequent annealing.

A disadvantage of such a method is the fact that during the cooling phase of the welded adjusting wheel, the weld is exposed to the risk of cracking. Thus, although it is true that with stronger cooling at lower temperatures the transformation becomes better and the subsequent tempering results in better toughness, the risk of cracking increases considerably. For this reason, it has heretofore been impossible to butt-weld the snap plates in the form of a closed ring body.

A further disadvantage is that the root of the weld seam in the base plate is uncontrollable and, for safety reasons, it is necessary to turn out at least the part of the root that is susceptible to cracking.

Recognizing more than the problem to be solved by the present invention, the present invention aims to minimize the risk of cracking even in the presence of notches in a method for manufacturing an adjusting wheel of the type mentioned at the beginning. It is an object of the present invention to make it possible to manufacture a regulating wheel which is optimal in terms of blade geometry and number of blades, even when subjected to very large loads due to steam force and centrifugal force.

Means for Solving the Problems The present invention has solved these problems as follows. That is, all the vane units are butt welded to each adjacent vane unit, base plate, and forceps in the form of a ring body that is closed over its entire surface.

Such a method offers the particular advantage of facilitating the testing of weld seams in the base plate and the cummer plate of the vane unit.

Embodiments The present invention will now be described in detail according to embodiments shown in the drawings: The adjustment wheel, only a portion of which is shown in perspective in FIG. It consists of The individual vane units with vanes 1, force A-plates 2 and base plates 3 are manufactured from solid material. In the embodiment shown, the material is a temperable, heat-resistant, highly alloyed CrMoV steel, for example X 22 CrMoV 121 according to DIN standard.

The cutter plate 2 and the base plate 3 each have two weld grooves 4 , which are filled with transverse seams 5 .

The beveling process is shown in FIG. The groove face 6 of the weld groove is U-shaped. Of course, the groove surface may have a ■ shape or any other suitable shape. The groove surface 6 terminates in a weld lip 7 forming a butt seam 13 . The welding lip 7 is located directly on the lower side 8 of the cover plate 2 facing the vane 1 and on the upper side 12 of the base plate 3.

The bottom seam 9 consists of a weld formed with filler metal by the so-called TIG welding method (TIG) K. For clarity, the welding lip 7 is shown before welding the bottom seam. Of course, this weld lip 7 is at least partially melted during welding and solidifies as a weld root.

Due to the arrangement of the welding lip 7 at the outermost end of the cover plate 2, the formed welding route is easy to post-process and inspect.

The fill seam 11 is formed by hand welding using a coated welding rod. Both groove surfaces 6 are joined to each other by forming weld beads alternately on one side and the other.

FIG. 3 shows the process by which individual blade units are joined by welding. The vane unit is assembled in the form of a ring body.

Welding rings 15 are then hermetically welded along the vane unit on both sides by tack welding 14. This is because the bottom seam welding is carried out in ~1 atmosphere of protective gas.

The bottom seam welding and the fill seam welding shown in FIG. 2 are then carried out, so that each vane unit is joined together with its adjacent vane unit as a ring body which is closed both at the cover plate 2 and at the base plate 3. be done.

The adjustment wheel that has been welded in this way is then subjected to heat treatment. That is, immediately after welding, the regulating shaft is directly heated from welding heat to a softening annealing temperature of about 700°C. During the annealing phase, isothermal transformations occur in the weld metal and heat affected zone. The tissue generated in this case is not technically available.

As a result, there is no risk of cracking during this processing step.

The reason for this is that the transformation stress at 700°C is slight, welding stress is removed, and the toughness is better than that of martensite. After softening annealing, the adjustment wheel is air cooled.

Machining is then performed, including all steps necessary to weld the adjustment wheel onto the disk 16 of the high-pressure rotor 17.

First, the weld ring 15 is removed, and both end surfaces of the adjustment wheel are turned to a predetermined size. In this case, especially the second
As indicated by reference numeral 10 in the figure, the welding root in the cummer plate 2 and the base plate 3 is cut out. That is, these weld roots and any weld cracks that may occur are cut out and polished. Next, a customary ultrasonic flaw detection test and magnetic particle flaw detection test are performed.

After testing, an important process of refining is performed. Therefore, the welding ring 15 is reattached in an airtight manner. This is because during annealing a protective gas such as alpine is supplied. Thermal refining involves firstly a quenching process consisting of heating above 1000°C and cooling with compressed air or spray, and secondly a tempering process consisting of heating to an annealing temperature of about 700°C and cooling in a furnace at room temperature. It can be divided into

After finishing the tempering, the base plate portion of the adjustment wheel is finish turned for welding onto the disc 16 of the high pressure rotor 17. The welding, shown schematically in FIG. 4, is carried out by means of a submerged arc welding process with a large U-groove seam 1'8.

FIG. 5 shows a machined adjustment wheel that is turned smoothly on both sides at the transition from the high-pressure rotor 17 to the vane unit. In this case, the weld root of the seam 18, which is prone to weld cracking, has been turned away. The adjusting wheel and the high-pressure rotor form an inseparable structural unit.

The embodiment shown in FIG. 6 has the advantage that the transverse seam joining the cup plate and base plate can be made small.

The blade unit machined from raw material has a thin base plate, for example 41 m thick, as well as a cover plate 2'. The base plates 2' are butt welded together to form a narrow rim. The transverse seam consists of a groove bottom seam 9 by TIG welding and a filler seam 11' applied in several layers by hand welding. A welding layer 19 is applied in the circumferential direction over the entire width of the plate by means of a submerged arc welding method, in particular automatically. This allows the thickness of the cummer plate as well as the base plate to be increased arbitrarily. A better 8 degree is obtained by reducing the range of manual welding.

In some cases, it is also possible to omit the filling seam 11', which is formed by hand welding with a coated welding rod, altogether.

In this case, the outer weld layer 19 is formed directly on the groove bottom seam 9 by TIG welding.

Instead of the TIG welded bottom groove seam 9 in the embodiments of FIGS. 2 and 6, the cummer plate and the base plate can also be joined by electron beam, plasma arc or laser beam welding methods. In such cases, the butt seams should also be correspondingly different.

In the embodiment shown in FIG. 7, cover plate 2 and base plate 3' are joined over their entire radial area at a butt joint 13 by electron beam welding. The significantly thicker base plate 3' has an inner circumferential weld layer 19 produced by submerged arc welding.

The base plate 3' may be a rim body of small thickness, similar to the cummer plate 2' of the embodiment of FIG.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a part of the adjustment wheel according to the present invention, FIG. 2 is an end view showing the butt welds of individual vane units, and FIG.
The figure shows a perspective view of the adjustment wheel welded onto the rotor, Figure 4 is a perspective view of the adjustment wheel welded and fixed onto the rotor, and Figure 5 shows the adjustment wheel on the rotor with finished processing. FIG. 6 is an end view showing a butt weld portion different from the example shown in FIG. 2, and FIG. 7 is a perspective view showing a still different butt weld portion. DESCRIPTION OF SYMBOLS 1...Blade, 2...Cover plate, 3...Base plate, 4...Welding groove, 5...Horizontal joint, 6...
... Groove surface, 7... Welding lip, 9... Groove bottom joint, 11... Filling joint, 13... Butt joint, 1
4... Tack welding seam, 15... Welding ring, 16
... Disc, 17... Rotor, 18... U-shaped groove joint, 19... Weld layer -N CQ +JP

Claims (1)

[Claims] 1. A method for manufacturing an adjustment wheel for a high-pressure rotor in a steam turbine, the method comprising CrMoV, which is a heat-resistant high-alloy steel.
Many vane units made of solid materials such as steel,
Assembled as one ring body and welded together at the base plate (3) and cover plate (2) of the vane unit, then the ring body is placed on the disc (16) of the high pressure rotor (17) after heat treatment and machining and testing. In the welding type, all blade units are attached to the base plate (3
) and the cover plate (2) are butt-welded in the form of a ring body closed over the entire surface. 2. After welding, the ring body is heated to a softening annealing temperature without cooling to cause isothermal transformation in the weld metal and heat affected zone, and after machining and testing, the ring body is tempered and welded. 2. A method according to claim 1, which provides the joint with the same properties as the base material. 3. At the butt joint (13) of the blade unit, a groove bottom seam (13) is formed by electron beam, plasma, laser beam or argon arc welding with or without filler metal. 9) and then both groove surfaces (6) formed by the weld groove (4)
2. A method as claimed in claim 1, in which the beads are joined by means of beads which are applied alternately to one grooved surface and to the other grooved surface to form a filled seam (11). 4. The vane units are welded together at the butt joint (13) with or without filler metal by an electron beam, plasma or laser beam welding method, according to claim 1. Method described. 5. After butt welding the base plate and cover plate, the radial dimensions of the base plate and cover plate are increased by applying beads extending in the circumferential direction of the adjustment wheel in multiple layers by submerged arc welding. A method according to claim 3 or 4. 6. An adjustment wheel welded onto the high-pressure rotor of a steam turbine, consisting of one ring body assembled with a number of vane units, and the vane unit is attached to its cover plate (2) and base plate (3). Butt seam (13
), characterized in that each vane unit is butt-welded to the respective adjacent vane unit both at the cover plate (2) and at the base plate (3). 7. An adjustment wheel welded onto the high-pressure rotor of a steam turbine, consisting of one ring body assembled with a number of vane units, and the vane unit is attached to its cover plate (2) and base plate (3). a welding lip (4) with a welding groove (4), the welding groove in the cover plate (2) consisting of a V-shaped groove or a U-shaped groove, forming one butt seam (13); 7), and the welding lip (7) is attached to the blade (2) of the cover plate (2).
1), the welding groove in the base plate (3) is also V.
consisting of a shaped bevel or U-shaped bevel, transitioning into a welding lip (7) forming a butt seam (13);
The welding lip (7) is attached to the vane (1) of the base plate (3).
), characterized in that each vane unit is butt-welded to the respective adjacent vane unit both at the cover plate (2) and at the base plate (3). ring. 8. At least one of both the cover plate (2) and the base plate (3) of each blade unit has a blade (1).
) consists of a narrow rim piece machined from a solid material, to which a welding layer (19) of arbitrary thickness is formed after being butt-welded as a ring body. , an adjustment wheel according to claim 6. 9. At least one of both the cover plate (2) and the base plate (3) of each blade unit has a blade (
1) together with a narrow rim piece machined from a solid material, onto which a welding layer (19) of arbitrary thickness is formed after being butt-welded as a ring body. The adjustment wheel according to claim 7.